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Flashcards · 9202 · Topic 7
Trends within the periodic table flashcards
15 cards on Topic 7, subtopics 3.7.1 to 3.7.2. Pick a subtopic or study them all.
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3.7.1 Group properties
- Group 1 metal + water: products, and the pattern equation
- The metal hydroxide (an alkaline solution) and hydrogen. 2M + 2H₂O → 2MOH + H₂
- Lithium, sodium and potassium with water: observations
- Lithium: floats, steady fizzing. Sodium: floats, melts into a ball, moves about quickly. Potassium: floats; the hydrogen ignites with a lilac flame.
- Compounds of Group 1 metals with non-metals
- Ionic compounds containing the M⁺ ion; white solids that dissolve to give colourless solutions.
- Halogens: form of the element, ion charge and trends down the group
- Diatomic molecules (F₂, Cl₂, Br₂, I₂). They form 1− halide ions with metals. Down the group: reactivity decreases; melting and boiling points increase.
- Appearance of fluorine, chlorine, bromine and iodine at room temperature
- Fluorine: pale yellow gas. Chlorine: pale yellow-green gas. Bromine: red-brown liquid. Iodine: grey-black solid.
- Chlorine water + lithium bromide solution: equation and what you see
- Cl₂ + 2LiBr → 2LiCl + Br₂ (ionic: Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂). The solution turns yellow-orange.
- Explain why Group 1 metals get more reactive down the group
- More energy levels: the outer electron is further from the nucleus with more shielding, so the attraction is weaker and the electron is lost more easily.
- Explain why halogens get less reactive down the group
- More energy levels: the outer level is further from the nucleus with more shielding, so the attraction for an incoming electron is weaker and an electron is gained less easily.
3.7.2 Transition metals
- Where are the transition metals, and what three properties do many of them have?
- In the centre of the periodic table, between Groups 2 and 3. Many form ions with different charges, form coloured compounds and are useful as catalysts.
- Transition metals compared with Group 1 metals
- Higher melting points (except mercury) and higher densities; stronger and harder; much less reactive, so they react far less vigorously with water and oxygen.
- Which transition metal is the melting-point exception?
- Mercury: liquid at room temperature, melting at −39 °C. The exception is for melting point only — its density is still high.
- Charge on the vanadium ion in V₂O₅, and the compound’s name
- Five O²⁻ give 10−, shared by two V ions: V⁵⁺. Vanadium(V) oxide.
- Name CuBr and give the formula of iron(III) nitrate
- CuBr: copper(I) bromide (Br⁻ is 1−, so Cu⁺). Iron(III) nitrate: Fe(NO₃)₃.
- Is every transition metal compound coloured?
- No — "many", not all. Zinc compounds and anhydrous copper(II) sulfate are white.
- Transition metal catalysts in the Haber and Contact processes
- Haber process: iron. Contact process (stage 2, SO₂ → SO₃): vanadium(V) oxide, V₂O₅.